This is from an otherwise forgettable 1983 movie called “Eddie Macon’s Run”, with John Schneider in the lead role. I stand to be corrected, but I think this is a Mossberg of some iteration being operated by Kirk Douglas. Does the bayonet lug point to some particular model of that era?
Forearm does scream Mossberg.
Mossberg 590
Not in 1983. This American Rifleman article claims 1987 introduction for the 590:
https://www.americanrifleman.org/articles/2020/4/8/mossberg-590-top-selling-pump-shotgun-of-2019/
Mossberg 500 ATP 8 SP
I stand corrected. I saw that mag cap and bayo lug and thought 590.
https://joesalter.ca/products/mossberg-military-shotgun-500-atp-8-sp-